On Tue, Nov 19, 2019 at 3:11 PM Paul Kocialkowski paul.kocialkowski@bootlin.com wrote:
Hi,
On Wed 13 Nov 19, 11:04, Patrik Jakobsson wrote:
On Tue, Nov 12, 2019 at 4:50 PM Paul Kocialkowski paul.kocialkowski@bootlin.com wrote:
Hi,
On Tue 12 Nov 19, 16:11, Paul Kocialkowski wrote:
Hi,
On Tue 12 Nov 19, 11:20, Patrik Jakobsson wrote:
On Thu, Nov 7, 2019 at 4:30 PM Paul Kocialkowski paul.kocialkowski@bootlin.com wrote:
psbfb_probe performs an evaluation of the required size from the stolen GTT memory, but gets it wrong in two distinct ways:
- The resulting size must be page-size-aligned;
- The size to allocate is derived from the surface dimensions, not the fb dimensions.
When two connectors are connected with different modes, the smallest will be stored in the fb dimensions, but the size that needs to be allocated must match the largest (surface) dimensions. This is what is used in the actual allocation code.
Fix this by correcting the evaluation to conform to the two points above. It allows correctly switching to 16bpp when one connector is e.g. 1920x1080 and the other is 1024x768.
Signed-off-by: Paul Kocialkowski paul.kocialkowski@bootlin.com
drivers/gpu/drm/gma500/framebuffer.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c index 218f3bb15276..90237abee088 100644 --- a/drivers/gpu/drm/gma500/framebuffer.c +++ b/drivers/gpu/drm/gma500/framebuffer.c @@ -462,6 +462,7 @@ static int psbfb_probe(struct drm_fb_helper *helper, container_of(helper, struct psb_fbdev, psb_fb_helper); struct drm_device *dev = psb_fbdev->psb_fb_helper.dev; struct drm_psb_private *dev_priv = dev->dev_private;
unsigned int fb_size; int bytespp; bytespp = sizes->surface_bpp / 8;@@ -471,8 +472,11 @@ static int psbfb_probe(struct drm_fb_helper *helper, /* If the mode will not fit in 32bit then switch to 16bit to get a console on full resolution. The X mode setting server will allocate its own 32bit GEM framebuffer */
if (ALIGN(sizes->fb_width * bytespp, 64) * sizes->fb_height >dev_priv->vram_stolen_size) {
fb_size = ALIGN(sizes->surface_width * bytespp, 64) *sizes->surface_height;fb_size = ALIGN(fb_size, PAGE_SIZE);if (fb_size > dev_priv->vram_stolen_size) {psb_gtt_alloc_range() already aligns by PAGE_SIZE for us. Looks like we align a couple of times extra for luck. This needs cleaning up instead of adding even more aligns.
I'm not sure this is really for luck. As far as I can see, we need to do it properly for this size estimation since it's the final size that will be allocated (and thus needs to be available in whole).
Ok now I understand what you meant. Actually vram_stolen_size is always page aligned so fb_size doesn't need any page alignment here.
I'm a bit confused here, what about the case where: unaligned fb_size < dev_priv->vram_stolen_size but aligned fb_size > dev_priv->vram_stolen_size ?
That can never happen since aligning fb_size will never cross a page boundary, and stolen_size is always on a page boundary. Not sure how to explain it on a good way but: If stolen_size = 4096, then fb_size is only more than stolen_size if it is actually > 4096 regardless if we align it or not.
Granted, it's a corner case, but I don't follow the logic of comparing aligned and unaligned sizes: it feels a bit like comparing two values of different units.
We can keep it if you think it makes the code more readable.
There is also no need to align for psbfb_create() since it also takes care of this.
For the other times there is explicit alignment, they seem justified too:
- in psb_gem_create: it is common to pass the aligned size when creating the associated GEM object with drm_gem_object_init, even though it's probably not crucial given that this is not where allocation actually happens;
- in psbfb_create: the full size is apparently only really used to memset 0 the allocated buffer. I think this makes sense for security reasons (and not leak previous contents in the additional space required for alignment).
What I would prefer is to have a single place where the alignment is made so any hardware requirements would be transparent to the rest of the code.
Mhh, I thought that psbfb_create needs to be aware of the alignment in the form of the pitch_lines variable to decide which 2d accel method can be used or not (depending on associated alignment requirements). I guess this makes for another reason to ditch the accelerated 2d accel support.
I was only thinking of the size alignment. Yes, ditching 2D would make life easier in this regard.
Best would be if alignment is only made in psb_gtt_alloc_range() and then store the actual size in struct gtt_range. That way we can just pass along that value to memset() and drm_gem_object_init() without caring about how it is adjusted.
What strikes me however is that each call to psb_gtt_alloc_range takes the alignment as a parameter when it's really always PAGE_SIZE, so it should probably just be hardcoded in the call to allocate_resource.
This is a remnant from trying to add support for 2D and/or overlay planes (don't really remember). Doesn't matter if it stays or goes away.
What do you think?
I suppose most of this is outside the scope of what you're trying to do so we can just leave it as is and I can clean it up later.
I guess my main change here was to switch from sizes->fb_width/height to sizes->surface_width/height anyway, yes. I can totally live without the final PAGE_SIZE align for fb_size too (even though I think it makes sense).
Feel free to let me know what you'd like to receive as a v2 here and I'll do that :)
Let's keep it as it is with the motivation that it increases readability.
Applied to drm-misc-next. Thanks
Your size calculation looks correct and indeed makes my 1024x600 + 1920x1080 setup actually display something, but for some reason I get an incorrect panning on the smaller screen and stale data on the surface only visible by the larger CRTC. Any idea what's going on?
I'm not seeing this immediately, but I definitely have something strange after having printed more lines than the smallest display can handle or scrolling, where more than the actual size of the fb is used.
Maybe this is related to using the PowerVR-accelerated fb ops, that aren't quite ready for this use case?
I'll give it a try with psbfb_roll_ops and psbfb_unaccel_ops instead to see if it changes something for me. Maybe it would help for you too?
Some quick feedback about that:
- psbfb_unaccel_ops gives a correct result where the scrolling area is bound to the smallest display;
Yes, this also works correctly for me.
- psbfb_roll_ops gives a working scrolling but bound to the largest display (so the current shell line becomes invisible on the smallest one eventually);
It's not panning at all for me. I never really found gtt rolling to be useful. It's a neat trick but I didn't have a problem with console scrolling speed to begin with. I might just remove it.
Yeah, I also don't understand what the hype of accelerating fbdev ops is about. I guess it could have been useful back when there were serious users of fbdev in userspace (aka directfb) but that's not really where things are going today. For console usage, I also find the software method fast enough.
- psbfb_ops gives the same issue as above and seems to add artifacts on top.
Did you try this on CDV? There's only 2D acceleration on Poulsbo and Oaktrail.
I tried this one on Poulsbo (the other gma500 platform I have around).
There's probably limited interest in working on that aspect on our side though. I'd be interested to know if it affects the issue you're seeing though.
Focus on your requirements and I'll look at the rest.
Sounds good to me, thanks a lot! I'll do according to what you'd like for a v2.
Cheers,
Paul
-Patrik
Cheers,
Paul
I suspect that the generic implementation is already bullet-proof for these kinds of use case.
Cheers and thanks for the feedback,
Paul
sizes->surface_bpp = 16; sizes->surface_depth = 16; }-- 2.23.0
-- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
-- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
-- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com